Streptococcus pneumoniae is one of the three leading causes of bacterial meningitis and the most common cause of bacterial pneumonia. Although S. pneumoniae is carried by 10-30% of normal individuals without incidence, alcoholism, diabetes mellitus, chronic renal disease, and smoking are associated with more frequent and serious pneumococcal pneumonia. Pneumococcal pneumonia begins abruptly with a shaking chill and high fever. Cough with production of sputum pink to rusty in color and pleuritic chest pain are also common. Those who survive without therapy suffer from a sustained fever, plueritic pain and reproductive cough that continue until a “crisis” occurs 5-10 days after the onset of the disease. The “crisis” is actually associated with effective levels of opsonizing antibodies reaching the lesion.
Pneumococcal infection has been treated in the past with penicillin and other β-lactam agents. However, in the last 15 years, strains have developed that show resistance to both penicillin and cephalosporin. Due to the rise in drug resistance, pneumococcal epidemiologic and vaccine development studies have become increasingly important. Since epidemiologic and vaccine development studies require the evaluation of carriage and serotype identification, methods of serotyping have also become increasingly important. The current method of serotyping individual isolates is a manual assay that is both time consuming and subjective. What is needed in the art, is an automated, rapid and objective method of serotyping S. pneumoniae and other pathogens.
Chlamydia are obligate intracellular bacteria of which four species of are known: C. pneumoniae, C. psittaci, C. pecorum and C. trachomatis. C. pneumoniae is implicated as a causative or additive agent in coronary artery disease (CAD). C. psittaci causes psittacosis or ornithosis which is contracted through inhalation of respiratory secretions or dust from droppings of infected birds. C. pecorum, on the other hand, is currently believed not to infect humans. With better ability to detect different species of Chlamydia, these accepted paradigms regarding the different species may change or be enlarged.
The more widely known Chlamydia species, Chlamydia trachomatis, is the most common bacterial sexually transmitted disease (STD) in the United States today. The U. S. Centers for Disease Control and Prevention estimates that more than four million new cases occur each year. The highest rates of C. trachomatis infection are in 15- to 19-year-old adolescents regardless of demographics or location. Pelvic inflammatory disease (PID), a serious complication of C. trachomatis infection, has emerged as a major cause of infertility among women of childbearing age. C. trachomatis can be transmitted during vaginal, oral, or anal sexual contact with an infected partner. A pregnant woman may pass the infection to her newborn during delivery, with subsequent neonatal eye infection or pneumonia. The annual cost of C. trachomatis infection is estimated to exceed two billion dollars.
Most chlamydial infections are silent, causing no symptoms. This makes infection with Chlamydia species especially harmful because the bacteria normally cause serious, and possibly permanent, health impairment by the time the infected individuals realize they have been infected. It is only after CAD has developed or infertility is found that infected persons discover they have been infected with Chlamydia bacteria.
For example, C. trachomatis is transmitted silently by sexual contact. Persons infected with C. trachomatis may experience abnormal genital discharge or pain during urination. These early symptoms may be mild. If symptoms occur, they usually appear within one to three weeks after exposure. Two of every three infected women and one or two of every four infected men have no symptoms whatsoever. As a result, often the disease may not be diagnosed and treated until complications develop. It is estimated that, in women, one-third of the C. trachomatis infections result in PID. Often these infections are not diagnosed until PID or other complications develop. In men, rarely, C. trachomatis infections may lead to pain or swelling in the scrotal area, which is a sign of epididymitis, an inflammation of a part of the male reproductive system located near the testicles. Left untreated, this condition, like PID in women, can cause infertility. C. trachomatis can also cause proctitis (inflamed rectum) and conjunctivitis (inflammation of the lining of the eye). The bacteria also have been found in the throat as a result of oral sexual contact with an infected partner. In tropical climates, a particular strain of C. trachomatis causes an STD called lymphogranuloma venereum (LGV), which is characterized by prominent swelling and inflammation of the lymph nodes in the groin. Complications may follow if LGV is not treated. This infection is currently very rare in the United States, though with the expansion of tropical diseases into the continental U.S., more cases may be seen in the future.
C. trachomatis infection can be confused with gonorrhea because the symptoms of both diseases are similar. The most reliable way to diagnose C. trachomatis infection is for a clinician to send a sample of secretions from the patient's genital area to a laboratory that will look for the C. trachomatis organism using one of a wide variety of quick and inexpensive laboratory tests. Although attempting to grow the organism in specialized tissue culture in the laboratory is one of the most definitive tests, it is expensive and technically difficult to perform, and test results are not available for three or more days.
Other test formats exist that provide more rapid diagnosis of C. trachomatis, but there are no tests available to distinguish between various species of Chlamydia. Once an infected person has been diagnosed with an impairment, such as CAD or PID, the current practice is to attribute the damage to a species of Chlamydia, based on the location of the impairment. For example, PID would suggest C. trachomatis infection, and CAD would suggest C. pneumoniae infection.
If an active infection with C. trachomatis is found, antibiotics are prescribed, such as a one-day course of azithromycin or a seven-day course of doxycycline. Other antibiotics such as erythromycin or ofloxacin also are effective. Pregnant women can be treated with azithromycin or erythromycin. Amoxicillin is also a safe alternative for treating pregnant women. Penicilin, which is often used for treating some other STDs, is not effective against C. trachomatis infections.
The ease of treatment of active C. trachomatis infection emphasizes the need to be able to diagnose infection by Chlamydial bacteria. If the Chlamydial species can be easily diagnosed, the damage due to infection can be prevented. Additionally, the ability to diagnose which species of Chlamydia the person has or has had can aid in treatment because the affected organs, such as the heart or fallopian tubes, can be more carefully examined for damage and more complete treatment can be provided.
The inability to determine the presence or past presence of different Chlamydia species bacteria has many costs, both nationally and individually. Each year up to one million women in the United States develop PID. As many as half of all cases of PID may be due to C. trachomatis infection, and many of these occur without symptoms. PID can result in scarring of the fallopian tubes, which can block the tubes and prevent fertilization from taking place. An estimated 100,000 women each year become infertile as a result of PID. In other cases, scarring may interfere with the passage of the fertilized egg down into the uterus. When this happens, the egg may implant in the fallopian tube, causing an ectopic or tubal pregnancy. This condition may be life threatening for the mother and may result in the loss of the fetus. PID is the most common cause of pregnancy-related death among poor teenagers in the inner cites and rural areas of the United States. The annual cost estimates exceed seven billion dollars.
What is needed are rapid and accurate tests that can differentiate the different species of Chlamydia. At the present time, though some tests exist for C. trachomatis, there may be many infections due to other species of Chlamydia that go undiagnosed and untreated. Additionally what is needed are tests that can determine the species of Chlamydia that previously infected the patient in order to track the progression of such infection.